I. Field of the Invention
The present invention is directed to a workpiece transfer device of the type employed with a transfer assembly to transfer workpieces from one press to another on an automated press line.
II. Description of the Prior Art
A typical cell in an automated press plant is generally comprised of a transfer assembly located between two presses for transferring workpieces from one press to another. Typically, a transfer assembly is comprised of two movable carriages. Each carriage is attached to the outside of a corresponding press. A flexible transfer unit, such as a table programmed to travel horizontally between the two presses, is positioned between the two carriage members and reachable by each carriage member's workpiece transfer device.
With this transfer assembly, a carriage member with its workpiece transfer device removes the workpiece from the press and places it on the flexible transfer unit. The transfer unit then moves horizontally toward the second carriage member to be removed by the second carriage's workpiece transfer device and transferred into the second press.
A disadvantage of this previous system is that it requires a multiple unit transfer assembly. Specifically, each carriage member is limited in the scope in which it can travel in a horizontal plane. Further, the programmer must realign the transfer unit to correspond with the line of conveyance between the two presses.
In other arrangements, a transfer assembly includes multiple workpiece transfer units which move along a track on a frame bridging the intermediate space between two presses.
Each transfer device is limited in the horizontal distance for which it may travel. Therefore, intermediate support frames are provided along the transfer route for placement of the workpiece within reach of the following transfer device. In this way, the workpiece to be transferred from one press to another is repeatedly picked up and conveyed by several transfer devices en route to another press as disclosed in U.S. Pat. No. 4,279,561.
Similar problems of requiring multi-transfer devices and correspondingly multi-positioning stages are experienced with this transfer unit. The bulky system also requires the operator to continually align the positioning stages so that the workpiece may be properly conveyed.